wallet: set m_version in coin control to default value

In future commits we assume that coin_control.m_version has a
value when making sure that we follow truc rules, so we should
give it a default value of CTransaction::CURRENT_VERSION.

src/wallet/coincontrol.h

@@ -109,10 +109,10 @@ public:
     int m_max_depth = DEFAULT_MAX_DEPTH;
     //! SigningProvider that has pubkeys and scripts to do spend size estimation for external inputs
     FlatSigningProvider m_external_provider;
+    //! Version
+    uint32_t m_version = CTransaction::CURRENT_VERSION;
     //! Locktime
     std::optional<uint32_t> m_locktime;
-    //! Version
-    std::optional<uint32_t> m_version;
     //! Caps weight of resulting tx
     std::optional<int> m_max_tx_weight{std::nullopt};
 

src/wallet/spend.cpp

@@ -1032,9 +1032,7 @@ static util::Result<CreatedTransactionResult> CreateTransactionInternal(
     FastRandomContext rng_fast;
     CMutableTransaction txNew; // The resulting transaction that we make
 
-    if (coin_control.m_version) {
-        txNew.version = coin_control.m_version.value();
-    }
+    txNew.version = coin_control.m_version;
 
     CoinSelectionParams coin_selection_params{rng_fast}; // Parameters for coin selection, init with dummy
     coin_selection_params.m_avoid_partial_spends = coin_control.m_avoid_partial_spends;